<!DOCTYPE html>
<html>
<head><meta name="generator" content="Hexo 3.9.0">
    

    

    



    <meta charset="utf-8">
    
    
    
    
    <title>Java web:Filter | 欢迎参观小灰灰的网站哟 ヾ(◍°∇°◍)ﾉﾞ ~ | It&#39;s founded on March 9, 2019 and the open source address for the blog notes https://github.com/YUbuntu0109/YUbuntu0109.github.io</title>
    <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
    
    <meta name="theme-color" content="#3F51B5">
    
    
    <meta name="keywords" content="Java web">
    <meta name="description" content="学习笔记 : Java web之过滤器简介Filter被称作过滤器或者拦截器,作为Servlet 2.3中新增的技术,可以实现用户在访问某个目标资源之前,对访问的请求和响应进行相应处理.其基本功能就是对Servlet容器调用Servlet的过程进行拦截,从而在Servlet响应处理前后实现一些特殊功能. Filter过滤器实现了javax.servlet.Filter接口.在Filter接口中定义">
<meta name="keywords" content="Java web">
<meta property="og:type" content="article">
<meta property="og:title" content="Java web:Filter">
<meta property="og:url" content="https://yubuntu0109.github.io/2019/05/02/Java-web-Filter/index.html">
<meta property="og:site_name" content="欢迎参观小灰灰的网站哟 ヾ(◍°∇°◍)ﾉﾞ ~">
<meta property="og:description" content="学习笔记 : Java web之过滤器简介Filter被称作过滤器或者拦截器,作为Servlet 2.3中新增的技术,可以实现用户在访问某个目标资源之前,对访问的请求和响应进行相应处理.其基本功能就是对Servlet容器调用Servlet的过程进行拦截,从而在Servlet响应处理前后实现一些特殊功能. Filter过滤器实现了javax.servlet.Filter接口.在Filter接口中定义">
<meta property="og:locale" content="en">
<meta property="og:updated_time" content="2020-03-31T12:36:02.533Z">
<meta name="twitter:card" content="summary">
<meta name="twitter:title" content="Java web:Filter">
<meta name="twitter:description" content="学习笔记 : Java web之过滤器简介Filter被称作过滤器或者拦截器,作为Servlet 2.3中新增的技术,可以实现用户在访问某个目标资源之前,对访问的请求和响应进行相应处理.其基本功能就是对Servlet容器调用Servlet的过程进行拦截,从而在Servlet响应处理前后实现一些特殊功能. Filter过滤器实现了javax.servlet.Filter接口.在Filter接口中定义">
    
        <link rel="alternate" type="application/atom+xml" title="欢迎参观小灰灰的网站哟 ヾ(◍°∇°◍)ﾉﾞ ~" href="/atom.xml">
    
    <link rel="shortcut icon" href="/favicon.ico">
    <link rel="stylesheet" href="//unpkg.com/hexo-theme-material-indigo@latest/css/style.css">
    <script>window.lazyScripts=[]</script>

    <!-- custom head -->
    

</head>

<body>
    <div id="loading" class="active"></div>

    <aside id="menu" class="hide" >
  <div class="inner flex-row-vertical">
    <a href="javascript:;" class="header-icon waves-effect waves-circle waves-light" id="menu-off">
        <i class="icon icon-lg icon-close"></i>
    </a>
    <div class="brand-wrap" style="background-image:url(/img/brand.jpg)">
      <div class="brand">
        <a href="/" class="avatar waves-effect waves-circle waves-light">
          <img src="/img/my-portrait.jpg">
        </a>
        <hgroup class="introduce">
          <h5 class="nickname">黄宇辉</h5>
          <a href="mailto:3083968068@qq.com" title="3083968068@qq.com" class="mail">3083968068@qq.com</a>
        </hgroup>
      </div>
    </div>
    <div class="scroll-wrap flex-col">
      <ul class="nav">
        
            <li class="waves-block waves-effect">
              <a href="/"  >
                <i class="icon icon-lg icon-home"></i>
                Homepage
              </a>
            </li>
        
            <li class="waves-block waves-effect">
              <a href="/archives"  >
                <i class="icon icon-lg icon-archives"></i>
                Archives
              </a>
            </li>
        
            <li class="waves-block waves-effect">
              <a href="/tags"  >
                <i class="icon icon-lg icon-tags"></i>
                Tags
              </a>
            </li>
        
            <li class="waves-block waves-effect">
              <a href="/categories"  >
                <i class="icon icon-lg icon-th-list"></i>
                Categories
              </a>
            </li>
        
            <li class="waves-block waves-effect">
              <a href="https://github.com/YUbuntu0109" target="_blank" >
                <i class="icon icon-lg icon-github"></i>
                Github
              </a>
            </li>
        
            <li class="waves-block waves-effect">
              <a href="https://space.bilibili.com/364361791" target="_blank" >
                <i class="icon icon-lg icon-link"></i>
                Bilibili
              </a>
            </li>
        
      </ul>
    </div>
  </div>
</aside>

    <main id="main">
        <header class="top-header" id="header">
    <div class="flex-row">
        <a href="javascript:;" class="header-icon waves-effect waves-circle waves-light on" id="menu-toggle">
          <i class="icon icon-lg icon-navicon"></i>
        </a>
        <div class="flex-col header-title ellipsis">Java web:Filter</div>
        
        <div class="search-wrap" id="search-wrap">
            <a href="javascript:;" class="header-icon waves-effect waves-circle waves-light" id="back">
                <i class="icon icon-lg icon-chevron-left"></i>
            </a>
            <input type="text" id="key" class="search-input" autocomplete="off" placeholder="Search">
            <a href="javascript:;" class="header-icon waves-effect waves-circle waves-light" id="search">
                <i class="icon icon-lg icon-search"></i>
            </a>
        </div>
        
        
        <a href="javascript:;" class="header-icon waves-effect waves-circle waves-light" id="menuShare">
            <i class="icon icon-lg icon-share-alt"></i>
        </a>
        
        <!-- add the background music on Mar 11,2019
        <div>
            <iframe frameborder="no" border="0" marginwidth="0" marginheight="0" width=280 height=52 src="//music.163.com/outchain/player?type=2&id=438801642&auto=1&height=32"></iframe>
        </div>
        -->
    </div>
</header>
<header class="content-header post-header">

    <div class="container fade-scale">
        <h1 class="title">Java web:Filter</h1>
        <h5 class="subtitle">
            
                <time datetime="2019-05-02T09:29:12.000Z" itemprop="datePublished" class="page-time">
  2019-05-02
</time>


            
        </h5>
    </div>

    


</header>


<div class="container body-wrap">
    
    <aside class="post-widget">
        <nav class="post-toc-wrap post-toc-shrink" id="post-toc">
            <h4>TOC</h4>
            <ol class="post-toc"><li class="post-toc-item post-toc-level-2"><a class="post-toc-link" href="#学习笔记-Java-web之过滤器"><span class="post-toc-number">1.</span> <span class="post-toc-text">学习笔记 : Java web之过滤器</span></a><ol class="post-toc-child"><li class="post-toc-item post-toc-level-3"><a class="post-toc-link" href="#简介"><span class="post-toc-number">1.1.</span> <span class="post-toc-text">简介</span></a></li><li class="post-toc-item post-toc-level-3"><a class="post-toc-link" href="#Filter-annotation"><span class="post-toc-number">1.2.</span> <span class="post-toc-text">Filter annotation</span></a><ol class="post-toc-child"><li class="post-toc-item post-toc-level-4"><a class="post-toc-link" href="#注解示例-拦截用户的所有请求"><span class="post-toc-number">1.2.1.</span> <span class="post-toc-text">注解示例-拦截用户的所有请求</span></a></li><li class="post-toc-item post-toc-level-4"><a class="post-toc-link" href="#注解示例-拦截不同方式的访问请求"><span class="post-toc-number">1.2.2.</span> <span class="post-toc-text">注解示例-拦截不同方式的访问请求</span></a></li></ol></li><li class="post-toc-item post-toc-level-3"><a class="post-toc-link" href="#FilterConfig-interface"><span class="post-toc-number">1.3.</span> <span class="post-toc-text">FilterConfig interface</span></a><ol class="post-toc-child"><li class="post-toc-item post-toc-level-4"><a class="post-toc-link" href="#getInitParameter-String-name"><span class="post-toc-number">1.3.1.</span> <span class="post-toc-text">getInitParameter(String name)</span></a></li></ol></li><li class="post-toc-item post-toc-level-3"><a class="post-toc-link" href="#Filter-application"><span class="post-toc-number">1.4.</span> <span class="post-toc-text">Filter application</span></a><ol class="post-toc-child"><li class="post-toc-item post-toc-level-4"><a class="post-toc-link" href="#Filter-实现用户自动登录"><span class="post-toc-number">1.4.1.</span> <span class="post-toc-text">Filter 实现用户自动登录</span></a></li></ol></li></ol></li></ol>
        </nav>
    </aside>


<article id="post-Java-web-Filter"
  class="post-article article-type-post fade" itemprop="blogPost">

    <div class="post-card">
        <h1 class="post-card-title">Java web:Filter</h1>
        <div class="post-meta">
            <time class="post-time" title="2019-05-02 09:29:12" datetime="2019-05-02T09:29:12.000Z"  itemprop="datePublished">2019-05-02</time>

            


            

        </div>
        <div class="post-content" id="post-content" itemprop="postContent">
            <h2 id="学习笔记-Java-web之过滤器"><a href="#学习笔记-Java-web之过滤器" class="headerlink" title="学习笔记 : Java web之过滤器"></a>学习笔记 : Java web之过滤器</h2><h3 id="简介"><a href="#简介" class="headerlink" title="简介"></a>简介</h3><p><em><code>Filter</code>被称作过滤器或者拦截器,作为Servlet 2.3中新增的技术,可以实现用户在访问某个目标资源之前,对访问的请求和响应进行相应处理.其基本功能就是对Servlet容器调用<code>Servlet</code>的过程进行拦截,从而在Servlet响应处理前后实现一些特殊功能. Filter过滤器实现了<code>javax.servlet.Filter</code>接口.在Filter接口中定义了三个方法,其代表Filter的生命周期,如下所示 :</em><br><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// 用于初始化过滤器</span></span><br><span class="line">init(FilterConfig filterConfig);</span><br><span class="line"><span class="comment">// 客户端请求时被调用(Filter所有的工作都集中在此方法中)</span></span><br><span class="line">doFilter(ServletRequest request,ServletResponse response,FilterChain chain);</span><br><span class="line"><span class="comment">// 在Web应用程序卸载时被调用</span></span><br><span class="line">destory();</span><br></pre></td></tr></table></figure></p>
<h3 id="Filter-annotation"><a href="#Filter-annotation" class="headerlink" title="Filter annotation"></a>Filter annotation</h3><p><em>简介 : <code>Servlet3.0</code>提供<code>@WebFilter注解</code>将一个实现了<code>javax.servlet.Filter</code>接口的类定义为过滤器,继而当我们在Web应用中使用过滤器时无需在web.xml文件中配置Filter映射 !</em></p>
<h4 id="注解示例-拦截用户的所有请求"><a href="#注解示例-拦截用户的所有请求" class="headerlink" title="注解示例-拦截用户的所有请求"></a>注解示例-拦截用户的所有请求</h4><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">@WebFilter</span>(filterName=<span class="string">"/MyFilter"</span> , urlPatterns= <span class="string">"/*"</span>)</span><br><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">MyFilter</span> <span class="keyword">implements</span> <span class="title">Filter</span> </span>&#123;</span><br><span class="line">    ···</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<h4 id="注解示例-拦截不同方式的访问请求"><a href="#注解示例-拦截不同方式的访问请求" class="headerlink" title="注解示例-拦截不同方式的访问请求"></a>注解示例-拦截不同方式的访问请求</h4><p><em>描述 : 根据被Servlet容器调用的方式来拦截指定的资源.其调用方式如下所示 :</em><br><figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">package</span> javax.servlet;</span><br><span class="line"></span><br><span class="line"><span class="comment">/**</span></span><br><span class="line"><span class="comment"> * Enumeration of filter dispatcher types.</span></span><br><span class="line"><span class="comment"> *</span></span><br><span class="line"><span class="comment"> * <span class="doctag">@since</span> Servlet 3.0</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"><span class="keyword">public</span> <span class="keyword">enum</span> DispatcherType &#123;</span><br><span class="line">    FORWARD,</span><br><span class="line">    INCLUDE,</span><br><span class="line">    REQUEST,</span><br><span class="line">    ASYNC,</span><br><span class="line">    ERROR</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure></p>
<p><em>下面以<code>FORWARD</code>(如果目标资源是通过<code>RequestDispatcher</code>的<code>forward()</code>方法访问时,该过滤器将会被调用)为例,演示Filter对转发请求的过滤效果.</em></p>
<ol>
<li><p><em>ServletTest : 将请求转发给index.jsp页面.</em></p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">@WebServlet</span>(<span class="string">"/ServletTest"</span>)</span><br><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">ServletTest</span> <span class="keyword">extends</span> <span class="title">HttpServlet</span> </span>&#123;</span><br><span class="line">	<span class="keyword">private</span> <span class="keyword">static</span> <span class="keyword">final</span> <span class="keyword">long</span> serialVersionUID = <span class="number">1L</span>;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> <span class="title">ServletTest</span><span class="params">()</span> </span>&#123;</span><br><span class="line">		<span class="keyword">super</span>();</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">protected</span> <span class="keyword">void</span> <span class="title">doGet</span><span class="params">(HttpServletRequest request, HttpServletResponse response)</span></span></span><br><span class="line"><span class="function">			<span class="keyword">throws</span> ServletException, IOException </span>&#123;</span><br><span class="line"></span><br><span class="line">		request.getRequestDispatcher(<span class="string">"/index.jsp"</span>).forward(request, response);</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">protected</span> <span class="keyword">void</span> <span class="title">doPost</span><span class="params">(HttpServletRequest request, HttpServletResponse response)</span></span></span><br><span class="line"><span class="function">			<span class="keyword">throws</span> ServletException, IOException </span>&#123;</span><br><span class="line">		doGet(request, response);</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
</li>
<li><p><em>FilterTest.java : 拦截index.jsp页面.</em></p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// Servlet 3.0</span></span><br><span class="line"><span class="meta">@WebFilter</span>(filterName = <span class="string">"/FilterTest"</span>, urlPatterns = <span class="string">"/index.jsp"</span>, dispatcherTypes = &#123; DispatcherType.FORWARD &#125;) 																				</span><br><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">FilterTest</span> <span class="keyword">implements</span> <span class="title">Filter</span> </span>&#123;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> <span class="title">FilterTest</span><span class="params">()</span> </span>&#123;</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">destroy</span><span class="params">()</span> </span>&#123;</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">doFilter</span><span class="params">(ServletRequest request, ServletResponse response, FilterChain chain)</span></span></span><br><span class="line"><span class="function">			<span class="keyword">throws</span> IOException, ServletException </span>&#123;</span><br><span class="line">		response.getWriter().println(<span class="string">"This is Filter !"</span>);</span><br><span class="line"></span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">init</span><span class="params">(FilterConfig fConfig)</span> <span class="keyword">throws</span> ServletException </span>&#123;</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
</li>
</ol>
<h3 id="FilterConfig-interface"><a href="#FilterConfig-interface" class="headerlink" title="FilterConfig interface"></a>FilterConfig interface</h3><p><em>简介 : 为了获取Filter程序在<code>web.xml</code>中的配置信息,Servlet API提供了一个FilterConfig接口,该接口封装了Filter程序在web.xml中的所有注册信息.并提供了一系列获取这些配置信息的方法.(同时适用于注解的哟 ~)</em></p>
<h4 id="getInitParameter-String-name"><a href="#getInitParameter-String-name" class="headerlink" title="getInitParameter(String name)"></a>getInitParameter(String name)</h4><p><em>描述 : 下面以接口FilterConfig接口中的<code>getInitParameter(String name)</code>方法为例,演示FilterConfig接口的作用.</em></p>
<ol>
<li><p><em>FilterConfigTest.java : 获取注解中指定名称的初始化参数值.</em></p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// 使用注解为该Filter设置初始化参数: initParams= &#123;@WebInitParam(name="encoding",value="utf-8")&#125;</span></span><br><span class="line"><span class="meta">@WebFilter</span>(filterName = <span class="string">"/FilterConfigTest"</span>, urlPatterns = <span class="string">"/MyServlet"</span>, initParams = &#123;</span><br><span class="line">		<span class="meta">@WebInitParam</span>(name = <span class="string">"encoding"</span>, value = <span class="string">"utf-8"</span>) &#125;)</span><br><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">FilterConfigTest</span> <span class="keyword">implements</span> <span class="title">Filter</span> </span>&#123;</span><br><span class="line"></span><br><span class="line">	FilterConfig filterConfig;</span><br><span class="line">	String characterEncoding = <span class="keyword">null</span>;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> <span class="title">FilterConfigTest</span><span class="params">()</span> </span>&#123;</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">destroy</span><span class="params">()</span> </span>&#123;</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">doFilter</span><span class="params">(ServletRequest request, ServletResponse response, FilterChain chain)</span></span></span><br><span class="line"><span class="function">			<span class="keyword">throws</span> IOException, ServletException </span>&#123;</span><br><span class="line"></span><br><span class="line">		response.setContentType(<span class="string">"text/html;charset=utf-8"</span>);</span><br><span class="line"></span><br><span class="line">		characterEncoding = filterConfig.getInitParameter(<span class="string">"encoding"</span>);</span><br><span class="line">		response.getWriter().println(<span class="string">"encoding的初始化参数的值为: "</span> + characterEncoding);</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">init</span><span class="params">(FilterConfig fConfig)</span> <span class="keyword">throws</span> ServletException </span>&#123;</span><br><span class="line">		<span class="keyword">this</span>.filterConfig = fConfig;</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
</li>
<li><p><em>FilterConfigTest.java : 获取web.xml中指定名称的初始化参数值(代码同FilterConfigTest.java),web.xml中的配置信息如下 :</em></p>
<figure class="highlight xml"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">&lt;?xml version="1.0" encoding="UTF-8"?&gt;</span></span><br><span class="line"><span class="tag">&lt;<span class="name">web-app</span> <span class="attr">xmlns:xsi</span>=<span class="string">"http://www.w3.org/2001/XMLSchema-instance"</span></span></span><br><span class="line"><span class="tag">	<span class="attr">xmlns</span>=<span class="string">"http://xmlns.jcp.org/xml/ns/javaee"</span></span></span><br><span class="line"><span class="tag">	<span class="attr">xsi:schemaLocation</span>=<span class="string">"http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"</span></span></span><br><span class="line"><span class="tag">	<span class="attr">id</span>=<span class="string">"WebApp_ID"</span> <span class="attr">version</span>=<span class="string">"4.0"</span>&gt;</span></span><br><span class="line">	<span class="tag">&lt;<span class="name">display-name</span>&gt;</span>Filter_basic<span class="tag">&lt;/<span class="name">display-name</span>&gt;</span></span><br><span class="line">	<span class="tag">&lt;<span class="name">welcome-file-list</span>&gt;</span></span><br><span class="line">		<span class="tag">&lt;<span class="name">welcome-file</span>&gt;</span>index.html<span class="tag">&lt;/<span class="name">welcome-file</span>&gt;</span></span><br><span class="line">		<span class="tag">&lt;<span class="name">welcome-file</span>&gt;</span>index.htm<span class="tag">&lt;/<span class="name">welcome-file</span>&gt;</span></span><br><span class="line">		<span class="tag">&lt;<span class="name">welcome-file</span>&gt;</span>index.jsp<span class="tag">&lt;/<span class="name">welcome-file</span>&gt;</span></span><br><span class="line">		<span class="tag">&lt;<span class="name">welcome-file</span>&gt;</span>default.html<span class="tag">&lt;/<span class="name">welcome-file</span>&gt;</span></span><br><span class="line">		<span class="tag">&lt;<span class="name">welcome-file</span>&gt;</span>default.htm<span class="tag">&lt;/<span class="name">welcome-file</span>&gt;</span></span><br><span class="line">		<span class="tag">&lt;<span class="name">welcome-file</span>&gt;</span>default.jsp<span class="tag">&lt;/<span class="name">welcome-file</span>&gt;</span></span><br><span class="line">	<span class="tag">&lt;/<span class="name">welcome-file-list</span>&gt;</span></span><br><span class="line"></span><br><span class="line">	<span class="tag">&lt;<span class="name">filter</span>&gt;</span></span><br><span class="line">		<span class="tag">&lt;<span class="name">filter-name</span>&gt;</span>FilterConfigTest<span class="tag">&lt;/<span class="name">filter-name</span>&gt;</span></span><br><span class="line">		<span class="tag">&lt;<span class="name">filter-class</span>&gt;</span>pers.huangyuhui.filter.filterconfig.FilterConfigTest<span class="tag">&lt;/<span class="name">filter-class</span>&gt;</span></span><br><span class="line">		<span class="tag">&lt;<span class="name">init-param</span>&gt;</span></span><br><span class="line">			<span class="tag">&lt;<span class="name">param-name</span>&gt;</span>encoding<span class="tag">&lt;/<span class="name">param-name</span>&gt;</span></span><br><span class="line">			<span class="tag">&lt;<span class="name">param-value</span>&gt;</span>gbk2312<span class="tag">&lt;/<span class="name">param-value</span>&gt;</span></span><br><span class="line">		<span class="tag">&lt;/<span class="name">init-param</span>&gt;</span></span><br><span class="line">	<span class="tag">&lt;/<span class="name">filter</span>&gt;</span></span><br><span class="line">	<span class="tag">&lt;<span class="name">filter-mapping</span>&gt;</span></span><br><span class="line">		<span class="tag">&lt;<span class="name">filter-name</span>&gt;</span>FilterConfigTest<span class="tag">&lt;/<span class="name">filter-name</span>&gt;</span></span><br><span class="line">		<span class="tag">&lt;<span class="name">url-pattern</span>&gt;</span>/MyServlet<span class="tag">&lt;/<span class="name">url-pattern</span>&gt;</span></span><br><span class="line">	<span class="tag">&lt;/<span class="name">filter-mapping</span>&gt;</span></span><br><span class="line"></span><br><span class="line"><span class="tag">&lt;/<span class="name">web-app</span>&gt;</span></span><br></pre></td></tr></table></figure>
</li>
</ol>
<h3 id="Filter-application"><a href="#Filter-application" class="headerlink" title="Filter application"></a>Filter application</h3><h4 id="Filter-实现用户自动登录"><a href="#Filter-实现用户自动登录" class="headerlink" title="Filter 实现用户自动登录"></a>Filter 实现用户自动登录</h4><p><em>案例描述 : 使用Cookie实现用户自动登录后,当客户端访问服务器的Servlet时,所有的Servelt都需要对用户的Cookie信息进行校验,这样势必会导致在Servlet程序中书写大量重复的代码.为了解决这个问题,可以在Filter程序中实现Cookie的校验.由于Filter可以对服务器的所有请求进行拦截,因此,一旦请求通过Filter程序,就相当于用户信息校验通过,然后Servelt程序就可以根据获取到的用户信息实现自动登录功能了.</em></p>
<ol>
<li><p><em>User.java : 封装用户的信息.</em></p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">package</span> pers.huangyuhui.filter.example.autologin;</span><br><span class="line"></span><br><span class="line"><span class="comment">/**</span></span><br><span class="line"><span class="comment"> * <span class="doctag">@ClassName</span>: User</span></span><br><span class="line"><span class="comment"> * <span class="doctag">@Description</span>: 封装用户的信息</span></span><br><span class="line"><span class="comment"> * <span class="doctag">@author</span>: HuangYuhui</span></span><br><span class="line"><span class="comment"> * <span class="doctag">@date</span>: May 1, 2019 7:24:26 PM</span></span><br><span class="line"><span class="comment"> * </span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">User</span> </span>&#123;</span><br><span class="line"></span><br><span class="line">	<span class="keyword">private</span> String username;</span><br><span class="line">	<span class="keyword">private</span> String password;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> <span class="title">User</span><span class="params">(String username, String password)</span> </span>&#123;</span><br><span class="line">		<span class="keyword">super</span>();</span><br><span class="line">		<span class="keyword">this</span>.username = username;</span><br><span class="line">		<span class="keyword">this</span>.password = password;</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> String <span class="title">getUsername</span><span class="params">()</span> </span>&#123;</span><br><span class="line">		<span class="keyword">return</span> username;</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">setUsername</span><span class="params">(String username)</span> </span>&#123;</span><br><span class="line">		<span class="keyword">this</span>.username = username;</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> String <span class="title">getPassword</span><span class="params">()</span> </span>&#123;</span><br><span class="line">		<span class="keyword">return</span> password;</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">setPassword</span><span class="params">(String password)</span> </span>&#123;</span><br><span class="line">		<span class="keyword">this</span>.password = password;</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
</li>
<li><p><em>login.jsp : 用户登录页面.</em></p>
<figure class="highlight html"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag">&lt;<span class="name">%@</span> <span class="attr">page</span> <span class="attr">language</span>=<span class="string">"java"</span> <span class="attr">contentType</span>=<span class="string">"text/html; charset=UTF-8"</span></span></span><br><span class="line"><span class="tag">    <span class="attr">pageEncoding</span>=<span class="string">"UTF-8"</span>%&gt;</span></span><br><span class="line"><span class="meta">&lt;!DOCTYPE <span class="meta-keyword">html</span>&gt;</span></span><br><span class="line"><span class="tag">&lt;<span class="name">html</span>&gt;</span></span><br><span class="line">	<span class="tag">&lt;<span class="name">head</span>&gt;</span></span><br><span class="line">		<span class="tag">&lt;<span class="name">meta</span> <span class="attr">charset</span>=<span class="string">"UTF-8"</span>&gt;</span></span><br><span class="line">		<span class="tag">&lt;<span class="name">title</span>&gt;</span>应用案例 : Filter实现用户自动登录<span class="tag">&lt;/<span class="name">title</span>&gt;</span></span><br><span class="line">	<span class="tag">&lt;/<span class="name">head</span>&gt;</span></span><br><span class="line">	<span class="tag">&lt;<span class="name">body</span>&gt;</span></span><br><span class="line">		<span class="tag">&lt;<span class="name">h3</span> <span class="attr">align</span>=<span class="string">"center"</span>&gt;</span>用户登录页面<span class="tag">&lt;/<span class="name">h3</span>&gt;</span></span><br><span class="line">		<span class="tag">&lt;<span class="name">hr</span>/&gt;</span></span><br><span class="line">			<span class="tag">&lt;<span class="name">form</span> <span class="attr">action</span>=<span class="string">"LoginServlet"</span> <span class="attr">method</span>=<span class="string">"post"</span>&gt;</span></span><br><span class="line">				<span class="tag">&lt;<span class="name">table</span> <span class="attr">width</span>=<span class="string">"380px"</span> <span class="attr">cellpadding</span>=<span class="string">"0"</span> <span class="attr">align</span>=<span class="string">"center"</span>&gt;</span></span><br><span class="line">					 <span class="tag">&lt;<span class="name">tr</span>&gt;</span></span><br><span class="line">					 	<span class="tag">&lt;<span class="name">td</span> <span class="attr">height</span>=<span class="string">"30"</span> <span class="attr">align</span>=<span class="string">"center"</span>&gt;</span>用户名<span class="tag">&lt;/<span class="name">td</span>&gt;</span></span><br><span class="line">					 	<span class="tag">&lt;<span class="name">td</span>&gt;</span><span class="tag">&lt;<span class="name">input</span> <span class="attr">type</span>=<span class="string">"text"</span> <span class="attr">name</span>=<span class="string">"userName"</span>/&gt;</span><span class="tag">&lt;/<span class="name">td</span>&gt;</span></span><br><span class="line">					 <span class="tag">&lt;/<span class="name">tr</span>&gt;</span></span><br><span class="line">					 <span class="tag">&lt;<span class="name">tr</span>&gt;</span></span><br><span class="line">					 	<span class="tag">&lt;<span class="name">td</span> <span class="attr">height</span>=<span class="string">"30"</span> <span class="attr">align</span>=<span class="string">"center"</span>&gt;</span>密<span class="symbol">&amp;nbsp;</span>码<span class="tag">&lt;/<span class="name">td</span>&gt;</span></span><br><span class="line">					 	<span class="tag">&lt;<span class="name">td</span>&gt;</span><span class="tag">&lt;<span class="name">input</span> <span class="attr">type</span>=<span class="string">"password"</span> <span class="attr">name</span>=<span class="string">"userPassword"</span>/&gt;</span><span class="tag">&lt;/<span class="name">td</span>&gt;</span></span><br><span class="line">					 <span class="tag">&lt;/<span class="name">tr</span>&gt;</span></span><br><span class="line">					 <span class="tag">&lt;<span class="name">tr</span>&gt;</span></span><br><span class="line">					 	<span class="tag">&lt;<span class="name">td</span> <span class="attr">height</span>=<span class="string">"40"</span> <span class="attr">align</span>=<span class="string">"center"</span>&gt;</span>自动登录时间<span class="tag">&lt;/<span class="name">td</span>&gt;</span></span><br><span class="line">					 	<span class="tag">&lt;<span class="name">td</span>&gt;</span></span><br><span class="line">					 		<span class="tag">&lt;<span class="name">input</span> <span class="attr">type</span>=<span class="string">"radio"</span> <span class="attr">name</span>=<span class="string">"autologin"</span> <span class="attr">value</span>=<span class="string">"$&#123;60*60 &#125;"</span>/&gt;</span>一小时</span><br><span class="line">					 		<span class="tag">&lt;<span class="name">input</span> <span class="attr">type</span>=<span class="string">"radio"</span> <span class="attr">name</span>=<span class="string">"autologin"</span> <span class="attr">value</span>=<span class="string">"$&#123;60*60*24 &#125;"</span>/&gt;</span>一天</span><br><span class="line">					 		<span class="tag">&lt;<span class="name">input</span> <span class="attr">type</span>=<span class="string">"radio"</span> <span class="attr">name</span>=<span class="string">"autologin"</span> <span class="attr">value</span>=<span class="string">"$&#123;60*60*24*7 &#125;"</span>/&gt;</span>一周</span><br><span class="line">					 		<span class="tag">&lt;<span class="name">input</span> <span class="attr">type</span>=<span class="string">"radio"</span> <span class="attr">name</span>=<span class="string">"autologin"</span> <span class="attr">value</span>=<span class="string">"$&#123;60*60*24*31 &#125;"</span>/&gt;</span>一个月</span><br><span class="line">					 	<span class="tag">&lt;/<span class="name">td</span>&gt;</span></span><br><span class="line">					 <span class="tag">&lt;/<span class="name">tr</span>&gt;</span></span><br><span class="line">					 <span class="tag">&lt;<span class="name">tr</span>&gt;</span></span><br><span class="line">					 	<span class="tag">&lt;<span class="name">td</span> <span class="attr">height</span>=<span class="string">"50"</span> <span class="attr">colspan</span>=<span class="string">"2"</span> <span class="attr">align</span>=<span class="string">"center"</span>&gt;</span></span><br><span class="line">					 		<span class="tag">&lt;<span class="name">input</span> <span class="attr">type</span>=<span class="string">"submit"</span> <span class="attr">value</span>=<span class="string">"登录"</span>/&gt;</span><span class="symbol">&amp;nbsp;</span><span class="symbol">&amp;nbsp;</span><span class="symbol">&amp;nbsp;</span><span class="symbol">&amp;nbsp;</span></span><br><span class="line">					 		<span class="tag">&lt;<span class="name">input</span> <span class="attr">type</span>=<span class="string">"reset"</span> <span class="attr">value</span>=<span class="string">"重置"</span>/&gt;</span></span><br><span class="line">					 		<span class="tag">&lt;<span class="name">span</span> <span class="attr">style</span>=<span class="string">"font-size:13px;color:red"</span>&gt;</span>$&#123;errorMsg &#125;<span class="tag">&lt;/<span class="name">span</span>&gt;</span></span><br><span class="line">					 	<span class="tag">&lt;/<span class="name">td</span>&gt;</span></span><br><span class="line">					 <span class="tag">&lt;/<span class="name">tr</span>&gt;</span></span><br><span class="line">				<span class="tag">&lt;/<span class="name">table</span>&gt;</span></span><br><span class="line">			<span class="tag">&lt;/<span class="name">form</span>&gt;</span></span><br><span class="line">	<span class="tag">&lt;/<span class="name">body</span>&gt;</span></span><br><span class="line"><span class="tag">&lt;/<span class="name">html</span>&gt;</span></span><br></pre></td></tr></table></figure>
</li>
<li><p><em>LoginServlet.java : 处理用户的登录请求.</em></p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">package</span> pers.huangyuhui.filter.example.autologin;</span><br><span class="line"></span><br><span class="line"><span class="keyword">import</span> java.io.IOException;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.ServletException;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.annotation.WebServlet;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.http.Cookie;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.http.HttpServlet;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.http.HttpServletRequest;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.http.HttpServletResponse;</span><br><span class="line"></span><br><span class="line"><span class="comment">/**</span></span><br><span class="line"><span class="comment"> * <span class="doctag">@ClassName</span>: LoginServlet</span></span><br><span class="line"><span class="comment"> * <span class="doctag">@Description</span>: 处理用户的登录请求</span></span><br><span class="line"><span class="comment"> * <span class="doctag">@author</span>: HuangYuhui</span></span><br><span class="line"><span class="comment"> * <span class="doctag">@date</span>: May 1, 2019 9:38:38 PM</span></span><br><span class="line"><span class="comment"> *</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"><span class="meta">@WebServlet</span>(<span class="string">"/LoginServlet"</span>)</span><br><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">LoginServlet</span> <span class="keyword">extends</span> <span class="title">HttpServlet</span> </span>&#123;</span><br><span class="line">	<span class="keyword">private</span> <span class="keyword">static</span> <span class="keyword">final</span> <span class="keyword">long</span> serialVersionUID = <span class="number">1L</span>;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> <span class="title">LoginServlet</span><span class="params">()</span> </span>&#123;</span><br><span class="line">		<span class="keyword">super</span>();</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">protected</span> <span class="keyword">void</span> <span class="title">doGet</span><span class="params">(HttpServletRequest request, HttpServletResponse response)</span></span></span><br><span class="line"><span class="function">			<span class="keyword">throws</span> ServletException, IOException </span>&#123;</span><br><span class="line"></span><br><span class="line">		String name = request.getParameter(<span class="string">"userName"</span>);</span><br><span class="line">		String password = request.getParameter(<span class="string">"userPassword"</span>);</span><br><span class="line">		String autoLogin = request.getParameter(<span class="string">"autologin"</span>);</span><br><span class="line"></span><br><span class="line">		<span class="comment">// 检查用户登录信息</span></span><br><span class="line">		<span class="keyword">if</span> (<span class="string">"YUbuntu0109"</span>.equals(name) &amp;&amp; <span class="string">"demo"</span>.equals(password)) &#123;</span><br><span class="line"></span><br><span class="line">			<span class="comment">// 将用户对象存入session域</span></span><br><span class="line">			User user = <span class="keyword">new</span> User(name, password);</span><br><span class="line">			request.getSession().setAttribute(<span class="string">"user"</span>, user);</span><br><span class="line"></span><br><span class="line">			<span class="keyword">if</span> (autoLogin != <span class="keyword">null</span>) &#123;</span><br><span class="line">				Cookie cookie = <span class="keyword">new</span> Cookie(<span class="string">"autologin"</span>, name + <span class="string">"-"</span> + password);<span class="comment">// 加密</span></span><br><span class="line">				cookie.setMaxAge(Integer.parseInt(autoLogin));</span><br><span class="line">				cookie.setPath(request.getContextPath());</span><br><span class="line">				response.addCookie(cookie);<span class="comment">// 发送自动登录的cookie</span></span><br><span class="line">			&#125;</span><br><span class="line">			response.sendRedirect(<span class="string">"index.jsp"</span>); <span class="comment">// 跳转到首页</span></span><br><span class="line"></span><br><span class="line">		&#125; <span class="keyword">else</span> &#123;</span><br><span class="line">			request.setAttribute(<span class="string">"errorMsg"</span>, <span class="string">"提示: 用户名或密码错误 !"</span>);</span><br><span class="line">			request.getRequestDispatcher(<span class="string">"/login.jsp"</span>).forward(request, response);</span><br><span class="line">		&#125;</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">protected</span> <span class="keyword">void</span> <span class="title">doPost</span><span class="params">(HttpServletRequest request, HttpServletResponse response)</span></span></span><br><span class="line"><span class="function">			<span class="keyword">throws</span> ServletException, IOException </span>&#123;</span><br><span class="line">		doGet(request, response);</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
</li>
<li><p><em>LoginServlet.java : 注销用户的登录信息.</em></p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">package</span> pers.huangyuhui.filter.example.autologin;</span><br><span class="line"></span><br><span class="line"><span class="keyword">import</span> java.io.IOException;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.ServletException;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.annotation.WebServlet;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.http.Cookie;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.http.HttpServlet;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.http.HttpServletRequest;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.http.HttpServletResponse;</span><br><span class="line"></span><br><span class="line"><span class="comment">/**</span></span><br><span class="line"><span class="comment"> * <span class="doctag">@ClassName</span>: LogoutServlet</span></span><br><span class="line"><span class="comment"> * <span class="doctag">@Description</span>: 注销用户登录的信息</span></span><br><span class="line"><span class="comment"> * <span class="doctag">@author</span>: HuangYuhui</span></span><br><span class="line"><span class="comment"> * <span class="doctag">@date</span>: May 1, 2019 9:47:49 PM</span></span><br><span class="line"><span class="comment"> *</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"><span class="meta">@WebServlet</span>(<span class="string">"/LogoutServlet"</span>)</span><br><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">LogoutServlet</span> <span class="keyword">extends</span> <span class="title">HttpServlet</span> </span>&#123;</span><br><span class="line">	<span class="keyword">private</span> <span class="keyword">static</span> <span class="keyword">final</span> <span class="keyword">long</span> serialVersionUID = <span class="number">1L</span>;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> <span class="title">LogoutServlet</span><span class="params">()</span> </span>&#123;</span><br><span class="line">		<span class="keyword">super</span>();</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">protected</span> <span class="keyword">void</span> <span class="title">doGet</span><span class="params">(HttpServletRequest request, HttpServletResponse response)</span></span></span><br><span class="line"><span class="function">			<span class="keyword">throws</span> ServletException, IOException </span>&#123;</span><br><span class="line"></span><br><span class="line">		<span class="comment">// 将Session会话中保存的User对象删除</span></span><br><span class="line">		request.getSession().removeAttribute(<span class="string">"user"</span>);</span><br><span class="line"></span><br><span class="line">		<span class="comment">// 将自动登录的Cookie删除</span></span><br><span class="line">		Cookie cookie = <span class="keyword">new</span> Cookie(<span class="string">"autologin"</span>, <span class="string">"msg"</span>);</span><br><span class="line">		cookie.setPath(request.getContextPath());</span><br><span class="line">		cookie.setMaxAge(<span class="number">0</span>);</span><br><span class="line">		response.addCookie(cookie);</span><br><span class="line">		response.sendRedirect(request.getContextPath() + <span class="string">"/index.jsp"</span>);</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">protected</span> <span class="keyword">void</span> <span class="title">doPost</span><span class="params">(HttpServletRequest request, HttpServletResponse response)</span></span></span><br><span class="line"><span class="function">			<span class="keyword">throws</span> ServletException, IOException </span>&#123;</span><br><span class="line">		doGet(request, response);</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
</li>
<li><p><em>AutoLoginFilter.java : 拦截用户登录的访问请求.</em></p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">package</span> pers.huangyuhui.filter.example.autologin;</span><br><span class="line"></span><br><span class="line"><span class="keyword">import</span> java.io.IOException;</span><br><span class="line"></span><br><span class="line"><span class="keyword">import</span> javax.servlet.Filter;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.FilterChain;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.FilterConfig;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.ServletException;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.ServletRequest;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.ServletResponse;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.annotation.WebFilter;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.http.Cookie;</span><br><span class="line"><span class="keyword">import</span> javax.servlet.http.HttpServletRequest;</span><br><span class="line"></span><br><span class="line"><span class="comment">/**</span></span><br><span class="line"><span class="comment"> * <span class="doctag">@ClassName</span>: AutoLoginFilter</span></span><br><span class="line"><span class="comment"> * <span class="doctag">@Description</span>: 拦截用户登录的访问请求</span></span><br><span class="line"><span class="comment"> * <span class="doctag">@author</span>: HuangYuhui</span></span><br><span class="line"><span class="comment"> * <span class="doctag">@date</span>: May 1, 2019 9:51:23 PM</span></span><br><span class="line"><span class="comment"> *</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"><span class="meta">@WebFilter</span>(filterName = <span class="string">"/AutoLoginFilter"</span>, urlPatterns = <span class="string">"/*"</span>)</span><br><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">AutoLoginFilter</span> <span class="keyword">implements</span> <span class="title">Filter</span> </span>&#123;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> <span class="title">AutoLoginFilter</span><span class="params">()</span> </span>&#123;</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">destroy</span><span class="params">()</span> </span>&#123;</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">doFilter</span><span class="params">(ServletRequest request, ServletResponse response, FilterChain chain)</span></span></span><br><span class="line"><span class="function">			<span class="keyword">throws</span> IOException, ServletException </span>&#123;</span><br><span class="line"></span><br><span class="line">		HttpServletRequest request2 = (HttpServletRequest) request;</span><br><span class="line">		Cookie[] cookies = request2.getCookies();</span><br><span class="line"></span><br><span class="line">		<span class="comment">// 获取一个名为`autologin`的cookie</span></span><br><span class="line">		String autoLogin = <span class="keyword">null</span>;</span><br><span class="line">		<span class="keyword">for</span> (<span class="keyword">int</span> i = <span class="number">0</span>; cookies != <span class="keyword">null</span> &amp;&amp; i &lt; cookies.length; i++) &#123;</span><br><span class="line">			<span class="keyword">if</span> (<span class="string">"autologin"</span>.equals(cookies[i].getName())) &#123;</span><br><span class="line">				autoLogin = cookies[i].getValue();</span><br><span class="line">				<span class="keyword">break</span>;</span><br><span class="line">			&#125;</span><br><span class="line">		&#125;</span><br><span class="line"></span><br><span class="line">        <span class="comment">// 验证用户登录信息</span></span><br><span class="line">		<span class="keyword">if</span> (autoLogin != <span class="keyword">null</span>) &#123;</span><br><span class="line">			String[] parts = autoLogin.split(<span class="string">"-"</span>);</span><br><span class="line">			String name = parts[<span class="number">0</span>];</span><br><span class="line">			String password = parts[<span class="number">1</span>];</span><br><span class="line">			<span class="keyword">if</span> (<span class="string">"YUbuntu0109"</span>.equals(name) &amp;&amp; <span class="string">"demo"</span>.equals(password)) &#123;</span><br><span class="line">                <span class="comment">// 将用户的登录信息封装到User对象并存入Sesssion域中,既而完成自动登录</span></span><br><span class="line">				User user = <span class="keyword">new</span> User(name, password);</span><br><span class="line">				request2.getSession().setAttribute(<span class="string">"user"</span>, user);</span><br><span class="line">			&#125;</span><br><span class="line">		&#125;</span><br><span class="line"></span><br><span class="line">		chain.doFilter(request, response);</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">	<span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">init</span><span class="params">(FilterConfig fConfig)</span> <span class="keyword">throws</span> ServletException </span>&#123;</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
</li>
</ol>

        </div>

        <blockquote class="post-copyright">
    
    <div class="content">
        
<span class="post-time">
    Last updated: <time datetime="2020-03-31T12:36:02.533Z" itemprop="dateUpdated">2020-03-31 12:36:02</time>
</span><br>


        
    </div>
    
    <footer>
        <a href="https://yubuntu0109.github.io">
            <img src="/img/my-portrait.jpg" alt="黄宇辉">
            黄宇辉
        </a>
    </footer>
</blockquote>

        
<div class="page-reward">
    <a id="rewardBtn" href="javascript:;" class="page-reward-btn waves-effect waves-circle waves-light">赏</a>
</div>



        <div class="post-footer">
            
	<ul class="article-tag-list"><li class="article-tag-list-item"><a class="article-tag-list-link" href="/tags/Java-web/">Java web</a></li></ul>


            
<div class="page-share-wrap">
    

<div class="page-share" id="pageShare">
    <ul class="reset share-icons">
      <li>
        <a class="weibo share-sns" target="_blank" href="http://service.weibo.com/share/share.php?url=https://yubuntu0109.github.io/2019/05/02/Java-web-Filter/&title=《Java web:Filter》 — 欢迎参观小灰灰的网站哟 ヾ(◍°∇°◍)ﾉﾞ ~&pic=https://yubuntu0109.github.io/img/my-portrait.jpg" data-title="微博">
          <i class="icon icon-weibo"></i>
        </a>
      </li>
      <li>
        <a class="weixin share-sns wxFab" href="javascript:;" data-title="微信">
          <i class="icon icon-weixin"></i>
        </a>
      </li>
      <li>
        <a class="qq share-sns" target="_blank" href="http://connect.qq.com/widget/shareqq/index.html?url=https://yubuntu0109.github.io/2019/05/02/Java-web-Filter/&title=《Java web:Filter》 — 欢迎参观小灰灰的网站哟 ヾ(◍°∇°◍)ﾉﾞ ~&source=My Personal Website For Blog" data-title=" QQ">
          <i class="icon icon-qq"></i>
        </a>
      </li>
      <li>
        <a class="facebook share-sns" target="_blank" href="https://www.facebook.com/sharer/sharer.php?u=https://yubuntu0109.github.io/2019/05/02/Java-web-Filter/" data-title=" Facebook">
          <i class="icon icon-facebook"></i>
        </a>
      </li>
      <li>
        <a class="twitter share-sns" target="_blank" href="https://twitter.com/intent/tweet?text=《Java web:Filter》 — 欢迎参观小灰灰的网站哟 ヾ(◍°∇°◍)ﾉﾞ ~&url=https://yubuntu0109.github.io/2019/05/02/Java-web-Filter/&via=https://yubuntu0109.github.io" data-title=" Twitter">
          <i class="icon icon-twitter"></i>
        </a>
      </li>
      <li>
        <a class="google share-sns" target="_blank" href="https://plus.google.com/share?url=https://yubuntu0109.github.io/2019/05/02/Java-web-Filter/" data-title=" Google+">
          <i class="icon icon-google-plus"></i>
        </a>
      </li>
    </ul>
 </div>



    <a href="javascript:;" id="shareFab" class="page-share-fab waves-effect waves-circle">
        <i class="icon icon-share-alt icon-lg"></i>
    </a>
</div>



        </div>
    </div>

    
<nav class="post-nav flex-row flex-justify-between">
  
    <div class="waves-block waves-effect prev">
      <a href="/2019/05/02/Java-web-Servlet-listener/" id="post-prev" class="post-nav-link">
        <div class="tips"><i class="icon icon-angle-left icon-lg icon-pr"></i> Prev</div>
        <h4 class="title">Java web:Servlet listener</h4>
      </a>
    </div>
  

  
    <div class="waves-block waves-effect next">
      <a href="/2019/05/02/Java-web-请求与响应/" id="post-next" class="post-nav-link">
        <div class="tips">Next <i class="icon icon-angle-right icon-lg icon-pl"></i></div>
        <h4 class="title">Java web:请求与响应</h4>
      </a>
    </div>
  
</nav>



    




















</article>

<div id="reward" class="page-modal reward-lay">
    <a class="close" href="javascript:;"><i class="icon icon-close"></i></a>
    <h3 class="reward-title">
        <i class="icon icon-quote-left"></i>
        thanks ~
        <i class="icon icon-quote-right"></i>
    </h3>
    <div class="reward-content">
        
        <div class="reward-code">
            <img id="rewardCode" src="/img/Wechat_appreciates.png" alt="打赏二维码">
        </div>
        
    </div>
</div>



</div>

        <footer class="footer">
    <div class="top">
        

        <p>
            
                <span><a href="/atom.xml" target="_blank" class="rss" title="rss"><i class="icon icon-lg icon-rss"></i></a></span>
            
            <span>This blog is licensed under a <a rel="license" href="https://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>.</span>
        </p>
    </div>
    <div class="bottom">
        <!-- 统计网站用户访问量. 技术支持：不蒜子(http://busuanzi.ibruce.info/) ————> Mar 13,2019 -->
        <p>
            <font style='font-size: 12px;color:springgreen'>
                    <div align="center">
                        <!-- 安装脚本 -->
                        <script async src="//busuanzi.ibruce.info/busuanzi/2.3/busuanzi.pure.mini.js"></script>
                        <!-- 安装标签 -->
                        <span id="busuanzi_container_site_pv">
                            ◎用户总访问量 : <span id="busuanzi_value_site_pv"></span> 次 ~ &nbsp&nbsp
                        </span>
                        <span id="busuanzi_container_site_uv">
                            ◎总访客数(（づ￣3￣）づ╭❤～) : <span id="busuanzi_value_site_uv"></span>人 ~
                        </span>
                    </div>
                </font>
            </p>
            <!---------->
            <p>
                <font style='font-size: 10px'>
                    <span>黄宇辉 &copy; 2019 - 2020</span>
                    <span>
                        
                        Blog source <a href="https://github.com/YUbuntu0109/YUbuntu0109.github.io" target="_blank">Github</a> 
                        Power by <a href="http://hexo.io/" target="_blank">Hexo</a>
                        Theme <a href="https://github.com/yscoder/hexo-theme-indigo" target="_blank">indigo</a>
                    </span>
                </font>
            </p>
        </div>
    </footer>
    </main>
    <div class="mask" id="mask"></div>
<a href="javascript:;" id="gotop" class="waves-effect waves-circle waves-light"><span class="icon icon-lg icon-chevron-up"></span></a>



<div class="global-share" id="globalShare">
    <ul class="reset share-icons">
      <li>
        <a class="weibo share-sns" target="_blank" href="http://service.weibo.com/share/share.php?url=https://yubuntu0109.github.io/2019/05/02/Java-web-Filter/&title=《Java web:Filter》 — 欢迎参观小灰灰的网站哟 ヾ(◍°∇°◍)ﾉﾞ ~&pic=https://yubuntu0109.github.io/img/my-portrait.jpg" data-title="微博">
          <i class="icon icon-weibo"></i>
        </a>
      </li>
      <li>
        <a class="weixin share-sns wxFab" href="javascript:;" data-title="微信">
          <i class="icon icon-weixin"></i>
        </a>
      </li>
      <li>
        <a class="qq share-sns" target="_blank" href="http://connect.qq.com/widget/shareqq/index.html?url=https://yubuntu0109.github.io/2019/05/02/Java-web-Filter/&title=《Java web:Filter》 — 欢迎参观小灰灰的网站哟 ヾ(◍°∇°◍)ﾉﾞ ~&source=My Personal Website For Blog" data-title=" QQ">
          <i class="icon icon-qq"></i>
        </a>
      </li>
      <li>
        <a class="facebook share-sns" target="_blank" href="https://www.facebook.com/sharer/sharer.php?u=https://yubuntu0109.github.io/2019/05/02/Java-web-Filter/" data-title=" Facebook">
          <i class="icon icon-facebook"></i>
        </a>
      </li>
      <li>
        <a class="twitter share-sns" target="_blank" href="https://twitter.com/intent/tweet?text=《Java web:Filter》 — 欢迎参观小灰灰的网站哟 ヾ(◍°∇°◍)ﾉﾞ ~&url=https://yubuntu0109.github.io/2019/05/02/Java-web-Filter/&via=https://yubuntu0109.github.io" data-title=" Twitter">
          <i class="icon icon-twitter"></i>
        </a>
      </li>
      <li>
        <a class="google share-sns" target="_blank" href="https://plus.google.com/share?url=https://yubuntu0109.github.io/2019/05/02/Java-web-Filter/" data-title=" Google+">
          <i class="icon icon-google-plus"></i>
        </a>
      </li>
    </ul>
 </div>


<div class="page-modal wx-share" id="wxShare">
    <a class="close" href="javascript:;"><i class="icon icon-close"></i></a>
    <p>扫一扫，分享到微信</p>
    <img src="//api.qrserver.com/v1/create-qr-code/?data=https://yubuntu0109.github.io/2019/05/02/Java-web-Filter/" alt="微信分享二维码">
</div>




    <script src="//cdn.bootcss.com/node-waves/0.7.4/waves.min.js"></script>
<script>
var BLOG = { ROOT: '/', SHARE: true, REWARD: true };


</script>

<script src="//unpkg.com/hexo-theme-material-indigo@latest/js/main.min.js"></script>


<div class="search-panel" id="search-panel">
    <ul class="search-result" id="search-result"></ul>
</div>
<template id="search-tpl">
<li class="item">
    <a href="{path}" class="waves-block waves-effect">
        <div class="title ellipsis" title="{title}">{title}</div>
        <div class="flex-row flex-middle">
            <div class="tags ellipsis">
                {tags}
            </div>
            <time class="flex-col time">{date}</time>
        </div>
    </a>
</li>
</template>

<script src="//unpkg.com/hexo-theme-material-indigo@latest/js/search.min.js" async></script>








<script>
(function() {
    var OriginTitile = document.title, titleTime;
    document.addEventListener('visibilitychange', function() {
        if (document.hidden) {
            document.title = 'Where are you going ?';
            clearTimeout(titleTime);
        } else {
            document.title = 'As long as you love me ~';
            titleTime = setTimeout(function() {
                document.title = OriginTitile;
            },2000);
        }
    });
})();
</script>



</body>
</html>
